At present a lighting load can be controlled by a phase-cutting dimmer or switch, where supply current of the dimmer or the switch flowing through the load may result in the lighting load flickering or failing to be disconnected, which can be addressed by an additional bypass load. The bypass load of the dimmer or the switch which is a virtual load can have the supply current flowing through the lighting load lowered to enable the dimmer or the switch to operate normally when the load is absent or very low.
In the prior art, the bypass load operates primarily with some simple element, for example, the bypass load is embodied simply as a capacitor or a powerful resistor. The inventors of the invention have identified from a research on the prior art that if the bypass load is composed of a resistor, then the lighting load may suffer from increased power consumption, lowered compatibility and a larger amount of generated heat; and if the bypass load is composed of a capacitor, then the capacitor may have an impedance characteristic of the lighting load altered and may result in the lighting load flickering or failing to be disconnected and in a narrowed dimming range of a dimmable lamp.